[Zope] Zope Calendar Product?

[Cliff Ford]

Hello friends,

I have been away from Zope for a while. I have a Zope 2.9.3 installation 
(no CMS or Plone) for which someone has requested a Calendar 
application. From the Zope sites it is not clear whether any suitable 
product is available. Could anyone recommend something? Alternatively, 
might it be an idea to use a stand-alone Calendar application and plug 
it into an I-frame?

Cliff